Processes for synthesis and purification of nondigestible fats

Abstract

A process for removing digestible fat from a crude reaction mixture comprising nondigestible fat and at least one digestible fat selected from the group consisting of digestible fats having fatty acid chains, comprising the steps of: (1) treating the crude reaction mixture with an aqueous solution comprising lipase at a pH sufficient to obtain soaps from the fatty acid chains; and (2) removing the soaps.

What is claimed is:  
     
       1. A process for removing digestible fat from a crude reaction mixture comprising nondigestible fat and at least one digestible fat selected from the group consisting of digestible fats having fatty acid chains, comprising the steps of: 
       (1) treating the crude reaction mixture with an aqueous solution comprising lipase at a pH sufficient to form soaps from the fatty acid chains; and  
       (2) removing the soaps;  
       wherein the nondigestible fat comprises polyol fatty acid polyesters; and 
       wherein the digestible fat is selected from the group consisting of monoglycerides, diglycerides, triglycerides, alkyl esters, insufficiently esterified polyol polyesters and mixtures thereof. 
     
     
       2. A process according to  claim 1  further comprising the step of adding surfactant and salt to the aqueous solution. 
     
     
       3. A process according to  claim 2 , wherein the salt is selected from the group selected from the group consisting of alkali metal salts, alkaline earth metal salts and mixtures thereof. 
     
     
       4. A process according to  claim 3 , wherein the salt is a calcium salt and wherein step (2) comprises precipitating and filtering out the soaps. 
     
     
       5. A process according to  claim 2 , wherein the surfactant is selected from the group consisting of alkali metal soaps, alkaline earth metal soaps, sucrose monoesters, sucrose diesters, and mixtures thereof. 
     
     
       6. A process according to  claim 1 , wherein the aqueous solution has a pH of from about 7 to about 10. 
     
     
       7. A process according to  claim 2 , comprising the steps of: 
       (1) treating the crude reaction mixture with an aqueous solution comprising lipase, surfactant and salt to form an aqueous mixture;  
       (2) adjusting the pH of the aqueous mixture to from about 9 to about 10 at least once during step (1).  
     
     
       8. A process according to  claim 7 , wherein the pH of the aqueous method is adjusted continuously. 
     
     
       9. A process according to  claim 1 , wherein the lipase is present at a level of from about 0.01% to about 1%, by weight of the solution. 
     
     
       10. A process according to  claim 1 , wherein the lipase specifically hydrolyzes fatty acid ester linkages of triglyceride at positions 1 and 3. 
     
     
       11. A A process according to  claim 1 , wherein the lipase nonspecifically hydrolyzes fatty acid ester linkages of triglyceride. 
     
     
       12. A process according to  claim 1 , further comprising the step of water-washing the nondigestible fat after the crude reaction mixture has been treated with the aqueous solution comprising lipase. 
     
     
       13. A process according to  claim 12 , wherein the digestible fat is selected from the group consisting of monoglycerides, diglycerides, triglycerides and mixtures thereof; and wherein the process comprises the step of: 
       (1) treating the crude reaction mixture with an aqueous solution comprising lipase, surfactant and salt to obtain glycerol and soaps; and  
       (2) removing the glycerol and soaps.  
     
     
       14. A process for synthesizing polyol fatty acid polyesters comprising the steps of: 
       (1) mixing ingredients comprising (a) unesterified first polyol having hydroxyl groups, (b) second polyol esterified with fatty acids, (c) basic catalyst, and (d) emulsifying agent to form a mixture of ingredients;  
       (2) reacting the mixture of ingredients at a temperature sufficient to obtain a crude reaction mixture comprising ingredients, reaction products and by-products;  
       (3) removing at least a portion of the by-products from the crude reaction mixture;  
       (4) further reacting the reaction products and ingredients from step (3) at a temperature and for a time sufficient to esterify at least about 50% of the hydroxyl groups of the first polyol; and  
       (5) treating the resulting product of step (4) with an aqueous solution comprising lipase at a pH sufficient to form soaps from the fatty acid chains of the esterified second polyol and by-products.  
     
     
       15. A process according to  claim 14 , further comprising the step of adding surfactant and salt to the aqueous solution. 
     
     
       16. A process according to  claim 14 , wherein step (4) proceeds for a time sufficient to esterify at feast about 75% of the hydroxyl groups of the first polyol. 
     
     
       17. A process according to  claim 14 , wherein step (4) proceeds for a time sufficient to esterify at east about 95% of the hydroxyl groups of the first polyol. 
     
     
       18. A process for synthesizing polyol fatty acid polyesters comprising the steps of: 
       (1) mixing ingredients comprising (a) unesterified first polyol having hydroxyl groups, (b) second polyol esterified with fatty acids, (c) basic catalyst, and (d) emulsifying agent to form a mixture of ingredients;  
       (2) reacting the mixture of ingredients at a temperature sufficient to obtain a crude reaction mixture comprising ingredients, reaction products and by-products;  
       (3) removing at least a portion of the by-products from the crude reaction mixture;  
       (4) further reacting the reaction products and ingredients from step (3) at a temperature and for a time sufficient to esterify at least about 50% of the hydroxyl groups of the first polyol; and  
       (5) treating the resulting product of step (4) with an aqueous solution comprising lipase at a pH sufficient to form fatty acids from the fatty acid chains of the esterified second polyol and by-products.  
     
     
       19. A process according to  claim 18 , wherein step (4) proceeds for a time sufficient to esterify at least about 75% of the hydroxyl groups of the first polyol. 
     
     
       20. A process according to  claim 18 , wherein step (4) proceeds for a time sufficient to esterify at least about 95% of the hydroxyl groups of the first polyol. 
     
     
       21. A process according to  claim 18 , wherein the unesterified first polyol comprises sucrose, the second polyol esterified with fatty acids comprises fatty acid triglyceride, and the by-products comprise glycerol. 
     
     
       22. A process according to  claim 18 , wherein step (4) proceeds for a time sufficient to form sucrose polyester comprising about 70%, by weight of the sucrose polyester, sucrose octa-esters. 
     
     
       23. A process according to  claim 21 , wherein the step of removing the fatty acids and glycerol comprises distilling to remove the acids and water-washing and centrifuging to remove the glycerol.